Indoor to outdoor transitions, and the subsequent occupant adaptation, impact thermal perception of occupants and their evaluation of a building. A mixed methods thermal comfort study in a classroom of Eindhoven University of Technology was conducted to provide a better understanding of thermal perception of students as they move into and adapt to their classroom environment. Data was collected over two weeks during heating period, with different heating set-points. A total of 384 students, in seven undergraduate level lectures, participated voluntarily. The thermal sensation vote, obtained at different time points through classes — 10 min, 20 min, and 45 min — was found to be significantly different (p 0.05). In the start of a lecture, perception varies primarily depending on the outside temperature, operative temperature, gender, and where the occupant came from. Comparing the two weeks' observations, second week having a 1.5 °C lower set-point, revealed that the most considerable differences occurred in the immediate response phase after indoor–outdoor transition. For nearly 20 min post transition, participants retain a thermal memory of their last exposure, gradually adapting as the lecture proceeds.